1. Field of the Invention
The present invention relates to a high voltage metal-oxide-semiconductor (HV MOS) transistor device and a method of fabricating the same, and more particularly, to an M-type HV MOS transistor device and a method of fabricating the same.
2. Description of the Prior Art
High voltage metal-oxide-semiconductor (HV MOS) transistor devices have been broadly utilized in CPU power supplies, power management systems, AC/DC converters, LCD/plasma TV drivers, automobile electronic components, PC peripheral devices, small DC motor controllers, and other consumer electronic devices due to being capable of enduring the high voltage provided by the electrical power system and having switching characterize together.
The HV MOS transistor device of the prior art is a circular device. A top view of the drain of the HV MOS transistor device is a circular pattern, and a top view of the source of the HV MOS transistor device is a circular ring-shaped pattern that surrounds the drain and has the same center of the circular pattern. Also, the drain of the HV MOS transistor device generally is electrically connected to a high voltage end of a power source, such as over 800 volts, so a voltage endurance structure is disposed between the drain and the source to raise a breakdown voltage of the HV MOS transistor device, and the HV MOS transistor device can operate normally under high voltage environment.
Since the channel width of the circular HV MOS transistor device is determined by a circumference of a ring region between the source and the drain, if the increase of the turn-on current of the HV MOS transistor device is required, the radius of the circular HV MOS transistor device should be increased accordingly, but the area of the circular HV MOS transistor device is also widely increased. For this reason, track race HV MOS transistor devices and M-type HV MOS transistor devices have been developed to increase the turn-on current of the HV MOS transistor device and minimize the area of the HV MOS transistor device together.
However, the breakdown voltage of the M-type HV MOS transistor device is smaller than the breakdown voltage of the circular HV MOS transistor device. When the circular HV MOS transistor device, the track race HV MOS transistor device and the M-type HV MOS transistor device are integrated in a same integrated circuit chip together, the breakdown voltage of the chip is limited by the breakdown voltage of the M-type HV MOS transistor device so as to reduce voltage endurance ability of the whole chip.
As a result, to raise the breakdown voltage of the M-type HV MOS transistor device and simultaneously to optimize the breakdown voltage of the chip integrated with the M-type HV MOS transistor device and the circular HV MOS transistor device is objective in this field.